Investigation of Sensitivity of Some Pulses and Agronomic Crops to Soil Residue of Idosulfuron-mesosulfurun Herbicide

To study the sensitivity of chick pea, bean, lentil, rapeseed, sugarbeet and tomato to soil residual concentration of Idosulfuron-mesosulfurun herbicide, an experiment was carried out under controlled conditions at the College of Agriculture, Ferdowsi University of Mashhad, Iran, in 2010. The studied factors were the 6 mentioned crops, and 7 levels of soil residual concentration of Idosulfuron-mesosulfurun herbicide (0, 0.0015, 0.0037, 0.0079, 0.015, 0.031 and 0.047 mg per kg of soil). The factorial experiment was carried out as a completely randomized design with three replications. Crops' emergence percentage was determined one week after their emergence. Plants' survival percentage and shoot and root biomass production were measured 30 days after their emergence. Results showed that all mentioned characteristics decreased significantly (P<0.01) in the presence of soil residue of the herbicide. Increasing Idosulfuron-mesosulfurun residual concentration in soil decreased emergence and shoot and root biomass production. Bean had the lowest shoot (44%) and root (66.78%) biomass loss and tomato had the highest shoot (96.38%) and root (89.64%) biomass loss. Based on ED50 index, pea (0.0079 mg/kg soil) was the most tolerant and tomato (0.0003 mg/kg soil) was the most susceptible crop to soil residues of Idosulfuron-mesosulfurun, and other crops ranked in between as: tomato< sugarbeet< rapeseed< lentil< bean< pea. In general, these results showed that soil residue of Idosulfuron-mesosulfurun can injure rotation crops and it is important to consider their sensitivity in rotation programming

Improved Activity of Imazethapyr onJimsonweed (Datura stramonium L.)

Introduction: An adjuvant has been defined as ‘a material that when added to a spray solution improves or modifies the performance of an herbicide’. There are five categories of adjuvants including drift retardants, extenders, stickers, wetters, and penetrants. The latter can chemically be divided into mineral or vegetable groups. Although some reports have found that vegetable oils are less effective than mineral oils, in view of the environmental concerns, the use of vegetable oils seem to be a suitable alternative to mineral oils because they offer a series of advantages such as being biodegradable and renewable resources. The plants essential oils are extracted from the medicinal plants not only have an adjuvancy activity at low concentrations but also have an herbicidal activity at high concentrations. It is believed that the benefit of vegetable oils as adjuvant can be related to their ability (i) to increase the drying period of the spray droplets during their fly time before impacting the leaves, (ii) to prevent bouncing off after impacting the leaves, (iii) to decrease contact angle of the droplet on the leaf surface and improve the spreading of them on the leaf surface, (iv) to delay crystallization of the active ingredient on the leaf surface, (v) to reduce the volatizing and photo-decomposing period of the herbicide active ingredient, (vi) to act as a penetrant agent on the leaf epicuticular wax in order to enhance the penetrability of the herbicide active ingredient into the plants. A fundamental part of all agrochemical researches is search to detect the natural chemicals offering adjuvancy properties to enhance the biological activity of agrochemicals. Therefore, we conducted a dose-response experiment to determine the potential influence of Blackseed, Fennel, Olibanum, and Rose oils as oily based-adjuvants in enhancing the imazethapyr activity against jimsonweed. Materials and Methods: The jimsonweed seeds were collected from plants in the fields of Qazvin and were stored in the dark at room temperature until further use. Bioassays were conducted in a greenhouse located on the Ferdowsi University of Mashhad, Iran. The seeds were washed every 1 h for 7 days for a total of 168 washings to remove seed germination inhibitors according to Andersen. They were sterilized with 5% (v/v) sodium hypochlorite solution for 10 min and rinsed with distillated water twice. Then, 25 jimsonweed seeds were sown in 2 L plastic pots filled with a mixture of sand, clay loam soil, and peat (1:1:1). The pots were irrigated three times a week. At the 1- and 2-leaf stage, the seedlings were thinned to 4 plants pot-1 and fertilized twice with 20 mL of a N:P:K (20:20:20) fertilizer with a concentration of 3% (w/v). The pots were irrigated every three days with tap water. Treatments were sprayed at the 4-leaf stage. Experimental design was a factorial arrangement with the 5 doses of imazethapyr (Pursuit® 10% SL) and the four essential oils at concentrations of 0.5 and 1% (v/v) in a completely randomized design with four replications. The emulsifier alkylarylpolyglycol ether was used to emulsify the substances in spray solution (95% oil + 5% emulsifier). Treatments were applied at 180 L ha-1 at 200 kPa using a calibrated moving boom sprayer with an 8002 flat-fan nozzle. Three weeks after spraying, biomass from each pot was collected and then weighted after oven-drying at 75°C for 48 h. The data were subjected to a non-linear regression analysis using the following logarithmic logistic dose-response model described. The relative potency that is the horizontal displacement between the two curves was calculated by the ratio of doses producing the same response. Results and Discussion: The slope of dose-response curves for jimsonweed to imazethapyr without or with each adjuvant were significantly similar as indicated by the same slope (b), so that they could be considered to be parallel. This indicates that the adjuvants were biologically inactive if they are used alone (without herbicide) at the tested concentration. Based on shoot fresh and dry weights of jimsonweed, the values of ED10 (6.47 and 7.50 g a.i. ha-1), ED50 (18.08 and 19.01 g a.i. ha-1), and ED90 (50.48 and 43.54 g a.i. ha-1) were obtained. All these values decreased in the presence of all the adjuvants. The relative potency values were significantly different from 1, indicating a significant enhancement in the imazethapyr activity when the adjuvants were added to the spray solution. Based on fresh weight of jimsonweed, the imazethapyr activity was improved up to 4.61-fold with addition of Fennel oil at 1% (v/v). Nonetheless, based on fresh weight of jimsonweed, it was improved up to 4.50-fold with addition of Olibanum at 1% (v/v). Based on dry weight of jimsonweed, the adjuvants were ranked according to their performance in improving imazethapyr activity as follows: Fennel > Olibanum > Blackseed > Rose when they were applied at 0.5% (v/v). But, at 1% (v/v), they were ranked as follows: Olibanum > Blackseed > Rose > Fennel. There are no reports available about the effect of the tested adjuvants as an adjuvant for herbicide, but similar studies were reported by Cabanne who found that the clodinafop-propargyl activity was enhanced up to 5- to 6-fold with adding pine essential oil (Pinus pinaster Ait.) to spray solution at 0.5% (v/v). Vegetable oils have also been found to be effective adjuvants for several post-emergence herbicides. Only in case of Blackseed oil, increasing the concentration had a significant effect to enhance the imazethapyr activity as compared to others. The benefit of concentration effect has formerly observed by researchers who reported that there was a strong concentration effect for rapeseed oil since their influence on phenmedipham and glyphosate uptake and activity was lower at 0.1% than at 1% (v/v). Conclusion: Since the main barrier for diffusing a hydrophilic herbicide such as imazethapyr into the leaf tissue is hydrophobic cuticle, thus oil based-adjuvants have been known to work best with them. On the other hand, a shift from non-environmentally friendly adjuvants to environmentally friendly (namely from mineral oil-based adjuvants to vegetable oil-based adjuvants) in adjuvant trend has been occurred due to being biodegradable and renewable. Thus, it is necessary to look for new essential oils offering adjuvancy properties to improve the efficacy of such foliar-applied herbicides because it is a straightforward approach to reduce the risk of adverse side-effects of herbicide via reducing herbicide dose needed to control suitable weeds. From the present study, it could be concluded that the oils Blackseed, Fennel, Olibanum, and Rose showed a strong adjuvancy properties for imazethapyr against jimsonweed and hence they could be suitable for developing and testing as an oily based-adjuvant. Though it is questioned whether crop selectivity could be threatened when these adjuvants are applied, further work is required under field conditions to answer this question

Feasibility of Reducing Sulfosulforun Herbicide Application in Wheat (Triticum aestivum L.) by Nitrogen Application Management

Introduction: Wheat is the main crop cultivated through out the world. Around 60 percent acreage of world farms belong to cereal crops from which, 33 percent belong to wheat production. In Iran wheat also is the dominant cereal crop accounting for almost 70 percent of cereal production. Iran wheat production in 2013 was about 14 million tones, and average grain yield 3750 Kg ha-1, is much lower than developing countries such as France ( 6800 Kg ha-1 ), Germany (7000 Kg ha-1 ) UK (7500 Kg ha-1 ) Japan ( 5000 Kg ha-1 ) and China (4900 Kg ha-1. The reasons for low yield include conventional planting methods, costly inputs, improper land preparation, imbalanced fertilizer application, lack of coordination between growers and mill owners, natural calamities and shortage of irrigation water and heavy weed infestation. Among these, poor management of fertilizers and weeds are the major cause of low wheat production in Iran. The use of herbicides for weed control in wheat is a common practice in management of weeds. But environmental and economical aspects, uncertainty in the long-term efficacy of chemical weed control methods are the most important issues that have caused researchers and farmers seeking to introduce an alternative to herbicides or to reduce the use of herbicides. Among herbicides, sulfonylurea’s such as sulfosulforun is one of the most important herbicides in wheat field. However, sulfosulforun is an effective herbicide for weed control. But its active soil residual, may damage rotational crops. Due to importance of nitrogen fertilizer management in wheat yield improvement, present study was designed to investigate the effect of nitrogen fertilizer application methods on weed management of wheat and reducing sulfosulforun herbicide under agro-climatic conditions of Mashhad, Iran. Materials and Methods: In order to evaluate sulfosulforun reducing dose, by nitrogen application management, an experiment was performed as split factorial plot, based on randomized complete block design with three replications at research farm, Faculty of Agriculture, Ferdowsi University of Mashhad, in 2012. Treatments included, nitrogen application methods (Broadcast and Band), the amount of nitrogen application (100, 200 and 400 kg ha-1 )(46% urea source) equal to 46, 92 and 184 kg ha-1 nitrogen per hectare, as complete factorial plots and sulfosulforun doses (100, 75 and 50 % of recommended dose (26.6 g (75% EC (emulsifiable concentrate)) as sub plots, applied at wheat tillering stage. Weed density and relative frequency were recorded 149, 177 and 210 days after wheat planting. Wheat biomass and seed yield per 1 m-2 were recorded at the end of the experiments. Analysis of variance of data was carried out with SAS software and for means comparison LSD (p≤0.05) test was used. Results and Discussion: Results showed that band application of nitrogen, reduced weed density and weed biomass significantly. By increasing nitrogen dose, mentioned parameters were increased significantly in both methods on nitrogen application. The highest weed density (29.27 plant m-2) were observed when sulfosulforun was not applied and the method of nitrogen application was broadcasted. The lowest weed density (12.78 plant m-2) observed at solfosulforun recommended dose and nitrogen band application treatment. The method of nitrogen application affected the amount of solfosulforun application. Based on the results, the effect of sulfosulforun at 75% and 50% of the recommended dose, didn’t effect significantly (p 0.05) on weed control when nitrogen applied in band with solfosulforun at recommended dose on weed control when nitrogen applied broadcast. Similar results were observed for wheat seed yield and wheat biomass. Wheat seed yield (343.40 g m-2) and wheat biomass (1141.50 g m-2) at solfosulforun recommended dose, when nitrogen applied in band, was not significantly different from 75% recommended dose of solfosulforun and nitrogen broadcast application method. Conclusion: Based on the results of experiment, the amount of nitrogen and its application method concludes an acceptable approach for wheat integrated weed management. It can optimize nitrogen fertilizer and solfusulforun herbicide usage, which are the main concerns in wheat production economically and ecologically. However nitrogen band application reduced the amount of nitrogen fertilizer and solfusulforun herbicide. Due to various factors affecting the competitive relationship between weeds and crops, it is suggested that in future the use of other herbicides, in different places and different crops to be considered

POST herbicide programs utilizing tribenuron for cleavers (Galium aparine L.) control in winter wheat cultivars

Cleavers (Galium aparine L.) causes severe problems in winter wheat (Triticum aestivum). Four field experiments were performed at Kayakenstky and Stalskiy regions, southern Russia over two growing winter seasons 2015 and 2016 to evaluate postemergence (POST) applications of herbicides (Flucarbazone, metsulfuron, 2,4-D, fluroxypyr, tribenuron, pyroxsulam and sulfosulfuron) applied alone or in tank mixtures on winter wheat cultivars. Wheat injury from herbicide application was minor, with the exception of pyroxsulam + sulfosulfuron in 2015, and tribenuron + pyroxsulam in 2016 at Kayakenstky. Best cleavers control was observed in treatments containing tribenuron. Cleavers were controlled least by metsulfuron (study 1) and flucarbazone (study 2), whereas cleavers had intermediate growth inhibitory responses to the other treatments. Tribenuron + fluroxypyr applied in wheat ‘Krasnodar 99', and tribenuron + pyroxsulam in wheat ‘Gerda’ resulted in enhanced grain yield with the value of 60% and 45.7%, respectively. Overall, tribenuron and herbicides containing tribenuron provided the most efficient control compared to the other herbicides and consistently maintained optimal grain yields in all cases. To improve weed control and to prevent a rapid development of herbicide resistance, tribenuron should be applied in combination with either fluroxypyr, pyroxsulam or metsulfuron. © 2019, © 2019 Informa UK Limited, trading as Taylor & Francis Group

Evaluation the Effect of Water Quality and Soil Nitrogen Content on Glyphosate Efficacy on Common Lambsquart(Chenopodium album L.) control

In order to study the effect of soil nitrogen content and water hardness on glyphosate efficacy on common lambsquart control, an experiment was carried out as a completely randomized design in a factorial arrangement with three replications in 2011 at the College of Agriculture, Ferdowsi University of Mashhad. Experimental treatments were included soil nitrogen content at 5 levels (0, 50, 90, 200 and 300 mg/kg soil), glyphosate doses at 7 levels (0, 75, 100, 125, 150, 175 and 200 % dose guideline glyphosate for common lambsquart), calcium carbonate concentration in water as index of water hardness at 5 levels ( 0, 100, 300, 600 and 1200 ppm). Spray was done at 8-10 common lambsquart leaf stage. 30 days after glyphosate spray, plants survival and shoot dry matter was measured. Results showed, herbicide rate, soil nitrogen content and water hardness had significantly affect (P<0.01) on growth and survival of common lambsquart. Increasing herbicide doses decreased common lambsquart survival and growth in pure water spraying. Increasing water hardness decreased glyphosate efficacy in control common lambsquart and increased glyphosate ED50 parameter. The lowest (1453.17 gr. a.i ha-1) and the highest (3424.45 gr. a.i ha-1) glyphosate ED50 for common lambsquart was observed in 0 and 1200 ppm of water hardness. Increasing soil nitrogen content from 18 to 300 (mg/kg soil) increased glyphosate efficacy in common lambsquart and glyphosate ED50 decreased from 3217.03 to 1612.58 (gr. a.i ha-1)

Evaluation the Effect of Corn (Zea mays L.) Sowing Pattern and Nitrogen Application Method on Herbicide Optimizing and Reducing Foramsulfuron (Equip®) Dose

Introduction: In the whole agro ecosystems, weeds had existence as unwanted plant that control of them is necessary. The competition between weeds and corn for moisture, light, nutrients during the growth season is induced reducing the quality and quantity of corn yield. Although the corn is high and powerful crop but is sensitive to competition with the weed and reduction of yield has been reported over 30%. Since the weeds are adapted to conditions, they are successful to completion and reducing the yield. So weed management is important in corn production. Chemical control has not been the unique and best way to manage the weeds and it reduce the sustainability of agro ecosystems. Although developing the herbicides, reduce the pressures caused by the weeds, but by developing rapidly the weed resistance to herbicides and increasing the environmental concerns and its high cost, today need to new, more immune and sustainable techniques for weed management. The main approach for sustainable weed management in an integrated weed management program is increasing crop competitiveness with weeds to reduce herbicide use. In this regard, the planting date, crop rotation, planting density, intercropping, planting pattern, fertilizer type, rate and application method are some of the most crop management strategies. Among the nutrients necessary for plants, nitrogen is the most nutrient in plant competition. Therefore, its application management plays a key role in reducing weed interference with crops and reduced herbicide use. Foramsulfuron herbicide from ALS inhibitors is a post-emergence sulfonylurea herbicide for the control of grasses and certain broadleaf weeds in maize. Unfortunately, these herbicides are also notorious for their ability to select resistant weed populations. Now, there are more weed species that are resistant to ALS-inhibiting herbicides than to any other herbicide group. In several cropping systems, ALS-inhibiting herbicides were used repeatedly as the primary mechanism of weed control. These herbicides exert strong selection pressure because of their high activity on sensitive biotypes at the rates used and because of their soil residual activity. So, the primary objective of this study was to determine the effect of some crop management strategies including sowing pattern and fertilizer application methods on herbicide optimizing and reducing foramsulfuron dose. Materials and Methods: In order to evaluate the effects of corn sowing pattern and nitrogen application methods on optimizing and reducing of foramsulfuron dose, a field experiment was conducted as split factorial, based on randomized complete block design with three replications at the Research Station, of Faculty of Agriculture, Ferdowsi University of Mashhad, in 2012. Treatments included, corn sowing methods (single-row with 75 cm distance, twine row as parallel on 75 cm width ridges sides and double row as zigzag on 75 cm width ridges sides) as main plots, factorial of nitrogen application methods (broadcast and band application), nitrogen source for fertilization was urea (400 kg ha-1), and foramsulfuron doses (100, 75, 50 and 0% of recommended dose (2 liter of commercial doses) applied at 4th corn leaf stage as sub plots.Weed density and frequency were recorded 10 days before corn harvesting and total weed biomass, corn biomass and seed yield were recorded at the end of the experiments per 1 m-2. Analysis of variance of data was carried out with SAS software and for means comparisons LSD (p≤0.05) test was used. Also The rectangular hyperbolic equation to describe the relationship between density and weed biomass and biomass and grain yield of maize was used Results and Discussion: Evaluation of weed flora indicated that 6 weed species (including 5 dicot. and 1 monocot.) including red root pigweed (Amaranthus retroflexus L.), black nightshade (Solanum nigrum L.), lambsquarters (Chenopodium album L.), field bindweed (Convolvolus arvensis L.), purslane (Potulaca oleracea L.) and barnyard (Echino clhloacrussgalli L.) were dominant species, with high evenness in the experimental plots. Amongst the mentioned weed species, the red root pigweed included about 74% of relative frequency and 80% of relative biomass of total weed biomass. Also results showed that the effect of sowing pattern on biomass and density of weeds and corn traits was not significant. However, band application of nitrogen versus broadcast application, increased weed density and biomass per m-2 25 and 10 percent, respectively and in the same way, increased corn height, kernel yield and biomass per m-2 7, 30 and 25 percent, respectively. Conclusion: It was concluded that by using double row sowing pattern along with band application of nitrogen, we can reduced foramsulfuron dose nearly 50 percent